Sol System, the cradle of mankind, and to this day the greatest, most invincible fortress of its mighty empire. There lay the citadel of Terra, The Golden Throne, the great enginuity of the Adeptus Mechanicus on Mars, and on a cold and distant moon of Saturn, Titan is the base of the Grey Knights. Fierce psykers and stalwart demon hunters, they are the Emperorís Hammer against the fell legions of Chaos.